Singlet oxygen is a reactive energetic form of oxygen which can be formed naturally by the interaction of electromagnetic radiation with atmospheric oxygen, singlet oxygen energy being released when the singlet oxygen molecule returns to the stable, or ground state.
It is well-known to artificially produce singlet oxygen using photosensitisers, which are compounds such as dyes that initiate a photochemical reaction. To produce singlet oxygen, a photosensitiser is excited by light radiation and subsequent excitonic hits between oxygen molecules and the excited photosensitiser cause the oxygen molecule to become excited from the ground triplet state to the singlet state.
Various therapeutic benefits have been attributed to the administration of singlet oxygen to a patient, and apparatus for producing singlet oxygen is known in the prior art. One such apparatus is described in our earlier patent application WO2012/056225. That apparatus comprises an activating unit through which atmospheric air is caused to flow, the activating unit comprising at least one light-emitting diode (LED) light source and at least part of a wall of the activating unit being coated with a photosensitiser. Irradiation of the photosensitiser by the LED causes some oxygen molecules in the flow of air through the activating unit to adopt the singlet oxygen state. Upon exiting the apparatus, these molecules return to the stable ground state, releasing the acquired energy into the air, which is inhaled by a patient. Typically, such a device may be used in the room in which the patient sleeps, providing a steady supply of energised oxygen.
It has now been found that apparatus of the type described above, which has previously been used to for the generation of singlet oxygen, also results in the delivery to the patient of gaseous nitrite. The apparatus may therefore be used for the treatment of conditions that may be ameliorated by the inhalation of air that contains gaseous nitrite.